844 SUMMABY OF CURRENT RESEARCHES RELATING TO 



ways, as tliin sheets and as a solution of the consistence of syrup ; 

 both must be kept in a damp atmosphere (under a glass shade, in case 

 the air by the sea does not contain enough moisture) ; the sheets then 

 remain soft, and have the proper consistence for cutting. The piece 

 to be imbedded is now fastened to a sheet, near to its edge, by a drop 

 of the liquid ; a piece of tissue-paper or gelatin paper is saturated 

 and softened with the solution and laid upon it, and on this notes as 

 to direction of cutting, &c., can be written ; other objects are laid on 

 the same sheet parallel to the first. Finally, the whole is covered 

 with a second and thinner sheet of glue, which quickly unites with 

 the first. The mass thus formed remains so transparent that the 

 prepared objects and notes are easily seen. The part of the sheet 

 which contains the objects is now again covered by the bell-glass ; 

 the exposed part dries rapidly and becomes harder. It is soon pos- 

 sible to cut sections ; the direction of cutting may be easily controlled 

 with the aid of a lens, owing to the transparency. The sections are 

 placed in water, and the glue dissolving readily, they are then fit for 

 examination. The only difficulty is to keep the glue soft enough ; if 

 it becomes too hard, it is impossible to make sections ; slight 

 moistening is of use in this case ; if the pieces of tissue are squeezed 

 up by the drying of the glue, it is remedied by the swelling which is 

 caused by this moistening. 



Cutting Sections of Myxomycetes, &c.* — For the lower vegetable 

 forms with naked protoplasm, osmic acid is recommended. The 

 currents in the protoplasm of Myxomycetes are instantly suspended, 

 and in a very short time the plasmodium is sufficiently hardened to 

 enable sections to be cut. 



Dayton's Cell.f — Fig. 199 represents a perpendicular sectional 

 view through the centre of a metallic die or punch. The sides A A, 

 Fig 199 however, should be bevelled to form a cutting edge 



at B B. By prolonging the sides and forming another 

 cutting edge at D D, rings for transparent cells may 

 be made, the raised edge forming an efficient pro- 

 tection to the cover-;^lass. 



The process of making the cell is thus described 

 by Dr. K. Dayton : — 



Drop melted sealing-wax or shellac upon a 

 slightly warmed and oiled surface of plate-glass, 

 until material has accumulated sufficient to a little 

 more than fill the die, press the die down quickly 

 and forcibly, and as the surplus resin exudes re- 

 volve the die so as to cut through to the glass. The cell produced 

 by this process will be polished more or less in proportion to the 

 finish the die has received in its manufacture. 



The advantages of this cell are, that it is easily and quickly made, 

 and can be modified as to form at slight expense. It can be attached 



* North. Microscopist, i. (1881) p. 201. 



t Amer. Journ. Micr., vi. (1881) p. 117 (1 fig.). 



I 



